Feature Article

Maintaining Polymer Colour and Clarity when Using Radiation Sterilisation Technologies

Posted in Sterilization Services by Camilla Andersson on November 5, 2012

Gamma and E-beam sterilisation methods are fast and effective. To take full advantage of these attributes, however, manufacturers should research the newest families of copolyesters that retain the glass-like clarity, colour stability and in-use toughness desired by clinical staff. 

The traditional use of autoclave sterilisation for medical devices is starting to decrease. The autoclave raises the temperature of the device up to 132°C by applying pressurised steam at 30 psi or 2 bar. Using high temperatures and steam to kill micro-organisms can cause many commonly used polymers to warp and distort, rendering the devices ineffective. In addition, molecular breakdown of some polymers can occur through hydrolysis, making the devices susceptible to breakage.

 Figure 1: Photographs of moulded resins before and after exposure to 50 kGy of gamma radiation.

The high temperatures needed for autoclave sterilisation may melt some plastic products and blunt sharp instruments. Further, autoclaving is not the most time-effective sterilisation method and it requires a significant amount of space to allow sufficient circulation around the devices and to accommodate sterilisation temperatures. However, autoclave sterilisation does have the benefit of rarely causing significant colour shift in the polymeric materials used for packaging or devices.

To overcome the limitations of autoclave sterilisation, healthcare professionals (HCPs) increasingly are turning to radiation-based sterilisation methods, which bring different challenges.

The move to radiation sterilisation
Gamma and E-beam are becoming the preferred sterilisation methods. These techniques reduce cost by means of high-volume throughput, speed and the elimination of high-temperature processing.

 Figure 1: b* colour measurements of Eastman specialty plastics and competitive resins after exposure to 50 kGy of gamma radiation.

Gamma or E-beam techniques allow HCPs to sterilise the whole kit at once, as the radiation penetrates outer packaging and reaches the devices inside. This eliminates unpacking and repacking steps, reducing the possibility for human error and increasing sterility.

 Figure 3: b* colour measurements of Eastman specialty plastics and competitive resins after exposure to 50 kGy of e-beam sterilisation.

The major disadvantage of gamma sterilisation is the need for a cobalt-60 radioactive source, requiring special handling and additional costs. E-beam radiation does not require a radioactive source; however, the technique has limitations in penetrating high-density materials such as metals.

It is also important to understand how to minimise the impact of a sterilisation method on the optical properties of devices through proper material choice.

One of the most critical effects of sterilisation on a material is a change in colour. Polymers exposed to radiation often shift in colour to yellow. For HCPs, any discolouration or property degradation is a cause for concern, because colour-coding and clarity play a vital role in the functionality and reliability of medical devices.

Clarity for clinical staff
It’s important for medical devices to maintain their glass-like clarity and avoid colour shift during the sterilisation process, as HCPs often rely on colour coding for quick identification. During medical procedures, HCPs must be able to quickly, efficiently and correctly identify and select the correct device based on colour. This is often used to indicate the size, type and function of the device. Subsequent quick execution can help to minimise medical errors and save time.

Additionally, excellent clarity gives HCPs unobstructed views to enable them to more easily and quickly identify colour changes in the blood during perfusion, foreign substances and bubbles and clots. It also allows them to easily monitor fluid levels and ensure that medicine is being properly delivered to the patient. The identification of potential issues before they develop can prevent more serious health problems such as embolisms or insertion-site infections.

Clarity also affects patient confidence, a more emotive but no less important consideration. A yellow or hazed device gives the impression that it is old or has been previously used. It’s essential that patients have the utmost confidence in the procedure they are undergoing and the devices that are being used.

 Figure 4: Photographs of moulded resins before and after exposure to 50 kGy of e-beam radiation.

The effects of sterilisation on the colour and clarity of a particular material depend on the material’s inherent chemistry as well as the sterilisation method used. With radiation sterilisation, the type and dose of radiation, together with the length of time the sterilised parts are left to rest after radiation, affect the final colour.

Colour-shifting study
Eastman Chemical conducted a study to further understand how gamma and E-beam radiation affect various types of polymers. The study included medical-grade copolyesters, gamma-stable polycarbonate (PC), transparent acrylonitrile butadiene styrene (TABS), and acrylic (PMMA). To determine the initial colour and any changes, the CIE Lab* scale was used. (CIE Lab was established by the International Commission on Illumination as a standard method for comparing colour values.)

The test results indicated that gamma and E-beam radiation can affect the colour of various polymer materials differently. After being exposed to 50 kGy of gamma radiation and measured three days after initial exposure, each of the materials showed a positive shift to higher b* values, indicating yellowing. The medical-grade copolyester showed the least amount of initial yellowing, with a shift of only about 2 b* units. The acrylic, TABS and PC materials all shifted more than 20 b* units.

After 42 days, the yellow colour of each of the gamma-radiated test samples faded to varying degrees. The colour of the medical-grade copolyester sample faded to a final b* value within 0.2 units of the initial colour. The final colour for the TABS and acrylic samples faded to within approximately 6 and 9 b* units of the initial colour, respectively, while the PC sample faded the least, with a final colour shift of 17 b* units from the initial point.

After the materials were exposed to E-beam radiation, similar results were observed. The medical-grade copolyester had the lowest yellow shift of any of the materials with a measured b* shift of 4.3 units. The TABS and acrylic shifted approximately 11 and 8 b* units, respectively, and the PC shifted the most, with a change of 17 b* units. Again, the colour faded towards the initial colour over time, with the medical-grade copolyester sample coming to within 0.5 b* units. The TABS and acrylic samples’ final colour shift was slightly less than 3 b* units, while the final colour of the PC sample was 9 b* units higher than that of the original.

Overall, medical-grade copolyesters showed insignificant colour shifts and had the lowest overall colour shift after radiation sterilisation among all the polymers tested. After gamma and E-beam sterilisation, one of the newest copolyesters, Eastman Tritan copolyester, exhibited best-in-class colour retention among the transparent polymers available for medical device applications.

Resistance to in-use abuse
Use of copolyesters for manufacturing medical devices minimises the colour shift or hazing after gamma or E-beam radiation sterilisation, thereby maintaining optimal clarity and colour and enabling medical device manufacturers to take full advantage of the speed and convenience of this type of sterilisation.

The recently developed copolyesters are heat-resistant, tough and sterilisation–stable, making them suitable for gamma or E-beam radiation. The new materials are also able to withstand exposure to blood, lipids and chemical agents, including isopropyl alcohol, disinfectants and bonding solvents.

Copolyesters that offer clarity and stability of colour and properties after sterilisation are suitable for use in a range of applications such as dialyser housings, syringes, blood separation devices, wound-treatment applications, blood-collection tubes, respiratory devices and IV components. Copolyesters are engineered to meet the performance demands of today’s injection-moulded medical devices whilst providing toughness, chemical resistance, processability and transparency.

Hospital conditions require medical devices to meet emergency treatment needs such as tapping and accidental knocking. The inherent toughness of copolyesters means that they are more resistant to everyday clinical abuse. They maintain their key mechanical and physical properties following sterilisation, which makes copolyesters well-suited to meet the material durability requirements of a hospital environment.

Resistance to solvents like lipids and isopropanol allows these versatile materials to be tailored to the specific needs of both the OEM and end user. Additionally, copolyesters are bisphenol A-free and are generally considered to be biocompatible, nontoxic, environmentally friendly materials, making them a good fit with the medical industry’s evolving green strategies.


Theo Wubbels
is Market Development Manager EMEA, Medical Specialty Plastics
Fascinatio Boulevard 602-614,
2909 VA, Capelle aan den Ijssel, Netherlands
Email: twubbels@eastman.com
Mobile: +31 61 383 2642

Find more content on:
No votes yet

Login to post comments

Comment viewing options

Select your preferred way to display the comments and click "Save settings" to activate your changes.

The issue, here, is not just

The issue, here, is not just that Judge is too limited a writer to pull it off, but that his wider world of context is too small even for sports. website traffic

I just added your blog to my

I just added your blog to my bookmark sites. thanks.Quality posts is the crucial to invite the visitors to visit the web page, that's what this page is providing.
spinal stenosis

I really most stretch my

I really most stretch my gratefulness towards such a legit post… You're really educated of what you're stating here. Really, keep up the colossal article posting! Exim Designs TV

Thanks for sharing nice

Thanks for sharing nice information with us. i like your post and all you share with us is uptodate and quite informative, i would like to bookmark the page so i can come here again to read you, as you have done a wonderful job. pnr status

check cashing carson

Really great post I am so impressed to see this article. I truly value the fact a person strategy these types of subjects from the remain stage associated with understanding as well as info. This can be a first-time; we been to at the website as well as started to be your own enthusiast. You're saved. Right now click on check cashing carson Make sure you continue publishing.

For everybody to know further

For everybody to know further about radiation and how this thing works and can cure. Nice article and appreciate much all the details. - best site for instagram followers

I think this is an

I think this is an informative post and it is very useful and knowledgeable. therefore, I would like to thank you for the efforts you have made in writing this article. best proxy sites

I was just browsing through

I was just browsing through the internet looking for some information and came across your blog. I am impressed by the information that you have on this blog. It shows how well you understand this subject. Bookmarked this page, will come back for more.spartagen xt

This post is really

This post is really magnificent. I really like this post. It is one of the best posts that I ve read in a long time. Thanks a lot for this really good post. I really appreciate it!renton locksmith

You have raised an important

You have raised an important issue..Thanks for sharing..I would like to read more current affairs from this blog..keep posting..
cool computer games

Thank you for posting such a

Thank you for posting such a great article! I found your website perfect for my needs. It contains wonderful and helpful posts. Keep up the good work!
you fit health club

It was wondering if I could

It was wondering if I could use this write-up on my other website, I will link it back to your website though.Great Thanks. seo service

about his or her health than

about his or her health than the patient.” To fuel this transformation, patients need better tools and better information.
manually do backlinks

Thanks for this great post, i

Thanks for this great post, i find it very interesting and very well thought out and put together. I look forward to reading your work in the future. engagements rings

He stated that some early

He stated that some early clinical experiments and trials in China on tissue engineering products were revealing responses that were not predicted by the in vitro and other preclinical tests, largely as a result of the effect of degrading polymer systems. This is clearly of major significance for the whole field of
High pr do follow links

David John

This is a fantastic website and I can not recommend you guys enough. Full of useful resource and great layout very easy on the eyes. Please do keep up this great work...the venus factor review


free clash of clans gems So it is interesting and very good written and see what they think about other people. castle clash mod apk

obat herbal gagal ginjal

Obat Herbal Gagal Ginjal Paling Aman.
Di tengah kondisi yang memprihatinkan, Saya menerima informasi bahwa ada Obat Herbal Gagal Ginjal terbuat dari kulit buah manggis yang mana dapat bantu menyembuhkan sakit ginjalnya. Tanpa ragu lagi ia segera mendatangi kantor obat penyakit jantung koroner amazon di Ibu Kota Jakarta untuk memperoleh produk ajaib tersebut. Sehabis memberlinya, beliau minum sebanyak 30 mili, 3 kali per-hari, ditambah teh Murbei, satu kali pada bangun tidur pagi dengan takaran yang lebih kental. Dengan waktu 10 hari bengkak-bengkak dibadannya sudah kempes, sakitnya juga hilang. Sebuah keadaan yang belum pernah ia alami sebelum minum Obat Tradisional sakit gagal ginjal. Setelah obat dokter habis dan terlambat cuci darah, kondisinya sudah pasti langsung menurun, namun sekarang sudah ada amazon Alami serta teh Murbei yang pasti menjadi "kawan" hidupnya. Segeralah mulailah pola hidup sehat dan tetap mengkonsumsi obat herbal gagal ginjal.

Rincian Obat Sakit Batu Ginjal amazon Plus
Pengobatan tradisional yang dapat diyakinkan yakni memakai obat alami sakit batu ginjal. Obat Herbal amazon Plus sangat luar biasa dalam memulihkan sakit batu ginjal dengan alamiah untuk organ-organ tubuh lainnya. Terapi dengan menggunakan Obat tradisional penyakit batu ginjal amazon Plus merupakan pengobatan yang sagat aman dan sudah terbukti ampuh mengobati penyakit batu ginjal sampai bersih, meskipun tidak menggunakan operasi. Queen Of Fruit adalah minuman herbal generasi terkini, dan merupakan kombinasi dari bahan-bahan alami yang mana telah melalui proses penelitian ilmiah selama bertahun-tahun. amazon di produksi menggunakan bioteknologi sangat canggih yang mengikutsertakan banyak ahli di bidangnya sehingga terjamin kualitas serta produk konsistensi obat herbal batu ginjal.

The image data obtained this

The image data obtained this way can then be utilised to build the 3D FE models needed for the simulation of biological processes of interes
backlinks uniqeu domains

I am really enjoying reading

I am really enjoying reading your well written articles. It looks like you spend a lot of effort and time on your blog. I have bookmarked it and I am looking forward to reading new articles. Keep up the good work. discover more

I am really enjoying reading

I am really enjoying reading your well written articles. It looks like you spend a lot of effort and time on your blog. I have bookmarked it and I am looking forward to reading new articles. Keep up the good work. discover more

It will be an advantage for

It will be an advantage for everybody to know further about radiation and how this thing works and can cure. Nice article and appreciate much all the details. - tinnitus medicine

This is one of the best posts

This is one of the best posts that I've read in my entire life. Thank you very much for publishing this post today. pinoy tv

polymer rocks

Really great post, Thank you

Really great post, Thank you for sharing This knowledge.Excellently written article, if only all bloggers offered the same level of content as you, the internet would be a much better place. Please keep it up! happy birthday wishes

And compared with the

And compared with the commission for discipline inspection, anti-corrupt department pay attention to investigation, audit notice from the source to shock and awe, http://www.alessandrocadario.com/lvbelts.php

Hi I found your site by

Hi I found your site by mistake when i was searching yahoo for this acne issue, I must say your site is really helpful I also love the design, its amazing!. I don’t have the time at the moment to fully read your site but I have bookmarked it and also add your RSS feeds. I will be back in a day or two. thanks for a great site.
Astuce Clash of Clans

Great and reliable source

Ohhhhh ! Great and reliable source posted really a very fantastic information . More information regarding Aashiqui 2 Songs Download check out website for free.


I read this article. I think You put a lot of effort to create this article. I appreciate your work.
Buy Facebook fans


Easily, the article is actually the best topic on this registry related issue. I fit in with your conclusions and will eagerly look forward to your next updates. Just saying thanks will not just be sufficient, for the fantasti c lucidity in your writing. I will instantly grab your rss feed to stay informed of any updates.
Buy Facebook Likes

What we should be grateful

What we should be grateful about is the fact that regardless of the unpleasant occurrences that we have no control over we still manage to uplift that with a lot of plausible actions to make things work. for.

dong ho deo tay gia re


First You got a great blog .I

First You got a great blog .I will be interested in more similar topics. i see you got really very useful topics , i will be always checking your blog thanks. highpr dofollow blog comment

I scoured the web for housing

I scoured the web for housing news, and I hit upon a real estate market news page, OC Housing News. While reviewing this web page, I came across a remarkable home seller's listing PDF download, For Sale by Owner Program. The housing news and real estate analysis on the site is super, the news coverage and cartoons are great, and I found the downloadable guides very useful. I advise checking out this page to survey its many features.

I should say only that its

I should say only that its awesome! The blog is informational and always produce amazing things. girlsdoporn

Took me time to read all the

Took me time to read all the comments, but I really enjoyed the article. It proved to be Very helpful to me and I am sure to all the commenters here! It’s always nice when you can not only be informed, but also entertained!

I have recently started a

I have recently started a blog, the info you provide on this site has helped me greatly. Thanks  for all of your time & work.  

This is regularly used to

This is regularly used to show the size, sort and capacity of the gadget. Consequent brisk execution can help to minimize therapeutic slips and spare time.

These are reliable and good

These are reliable and good data you provided. It will be an advantage for everybody to know further about radiation and how this thing works and can cure. Nice article and appreciate much all the details. - London Piano Institute